Is Ultra Instinct powerful than Super Saiyan Blue ?

In the anime, Goku uses Ultra Instinct to fight against Jiren and Kelfa (Tournament of Power arc)... is UI a power-up transformation like how SSJ, SSGB are ? Or is it just that his instincts are sharpened in his base form and he uses the improved fighting instincts to battle against his enemies ? If it is his insitincts alone being improved can he stack that form with his Super Saiyan blue form to have increased battle power and at the same time have good fighting instincts ?